Saturday, December 12, 2009

I got an email asking about solar and wind options for housing. Since I am planning to build an energy efficient house north of 49 degrees (in Canada) and have done a lot of thinking on this topic, I decided to share the following and now make it available as a blog post.

1. House design is essential. I plan to re-route all hot air evacuations (bathroom fan, kitchen fan, clothes dryer (if we get one) exhaust etc.) into either a thermal bus or to tie them directly to a year round greenhouse to use the thermal energy for growing food.

2. IMPORTANT: Always do the “Net” energy calculations. For example – having cheap, Chinese made solar powered, LED lights to power your walkway instead of investing in a proper system is a waste of time and an affront to the environment if you have to throw out something that broke in one year and took 25 times as much energy to make as it saved. For example, I bought these little solar powered lights at Home Depot, which lasted only about 250 days. When I took them apart, I discovered the culprit – a single AA rechargable battery was the only power source. These usually do not last more than 250 charging cycles and if you connect one to a daily charge routine, it will burn out in less than a year. Net result: I actually polluted more by buying cheap goods to save energy.

3. I also plan to use wood heating with a proper catalytic converter (avoids most carbon pollution) to warm the house on winter days as we have ample wood for cooking etc. The house we are choosing has a small horizontal footprint and is 2.5 stories high, which allows thermal energy to be more efficient.

4. I'm putting the shower and kitchen on the top floor then using a diverter valve to reroute the entire waste water into the flooring for either keeping the house cool in summer or heating in the winter.

5. After the electrical inspectors give the final OK, I am moving to 12 or 24 VDC power for all lighting in the house and possibly some USB outlets. All lighting will be 12/24 VDC LED indirect. This saves tons of energy over trying to convert a 12/24VDC battery array into 110 AC (or in your case 220 VAC, which would be less efficient). Most solar and wind systems use 12 or 24 VDC as the charging output. Energy can neither be created nor destroyed and it is a lossy process to convert energy. The biggest culprit is usually thermal energy as an unwanted byproduct (think of hot transformers). If you must convert, try to capture the byproduct (place the converters in a place that needs heating).

5. My wife and I are investigating thermal heating systems. These seem to make a lot of sense as they can be used in both the summer and winter. In North America, there is an relevant organization that has members; there might be a similar system in the UK - http://www.geoexchange.org/

6. In order to use wind energy in a micro manner, there are lots of manufacturers and the kits are not that hard to figure out. The first thing you have to do is check out the MET office to find out if it will work in your location. Wind speed must be at a minimum of 5 metres per second to work. The Canadian map showed us that in our case, we have sufficient wind. http://www.windatlas.ca/en/nav.php?field=E1&height=50&season=ANU&no=45.

7. Solar kits are also not that complicated. Study up on it and note the major components – collectors/charge controllers, battery array/inverters or converters then do the calculations. You have to figure out what you want to use the property for before you can plan a system. In our case, assuming we only go there on the weekends, we can go with less collections and a bigger battery array as the battery array will recharge during weekdays. If we lived there full time, we would have to use more collectors. Most manufacturers of repute (Siemens, etc/) will have all the calculations available. There are some good resources online for this too. Here is one: http://midsummerenergy.co.uk/solar_panel_information/solar_panel_calculator.html#nogo

8. Look into evacuated solar tubes. These work in very low temperatures (as low as –40 degrees Celsius) and can deliver off grid water at 65 degrees Celsius. They work by having no gas (a vacuum) in between the outer tube and the inner collector. This collects energy radiated from the sun without the atmosphere moving the heat away and harvests it via the manifold. http://www.solarthermal.com/products.asp These can take care of big things like hot water tanks.

9. If you use your property for weekends only like me, you might want to consider a Linux micro kernel running a small routine that can be used to “wake up” the house. For example, if you have a grid tied-hot water system, you could invoke a cron job that turns your hot water heater on and off remotely so you’re not paying for energy you don’t need. Another option is to move to a EU style JIT hot water heater (tank-less system).

10. For certification, The SRCC (Solar Rating and Certification Corporation) is the key solar collector certifying body for the US and Canada. Make sure everything you use has passed the minimum criteria for this.

11. My thoughts on this are that when I buy my supplies, I want to do it with a company that has been around, been certified and is backed by a manufacturer with a warranty and good history, and someone who has a physical office I can identify and walk into. Too many snake oil vendors on the web.

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